ef: a tale of memories (TV)

During the first episode when Hiro was in front of the church, a piece of paper flew pass by him. If you have good eyes, that paper actually has "Nice Boat" written on it which is a meme based on the last episode delay of School Days.

The pages in Chihiro's diary have a watermark of Utamaru from Da Capo. Naru Nanao (ef character designer) was the character designer for the DC series.

ef actually stands for euphoric field the word spelled out by the first letters of the names of each episode

Miyamura Miyako's behavior in the first episodes resembles Suzumiya Haruhi - even some trademark lines (notably the "Zenzen" line) are used.

Many of the POV (camera Point Of View) used in the first half of the series appear to be tributes to other shows, notably Evangelion (the abandoned Train Station scenes), Haruhi Suzumiya (inside-the-locker P.O.V.), Negima?! (umbrellas on the second episode) and Nodame Cantabile (slide shows).

Episode 5: Arround 16:09, young Kei hold a manga of Card Captor Sakura.

Five of theme songs used in ef anime and games can be abbreviated into "ef": euphoric field (ef - a tale of melodies anime opening theme), ebullient future (ef - a tale of melodies anime opening theme) eternal feather (a.k.a "yuukyuu no tsubasa", anime's last episode's ending theme and opening theme of game ef - the first tale), emotional flutter (opening theme of game ef - the latter tale) and ever forever (ending theme of ef - a fairy tale of the two).

In the opening and 'eyecatches',parts of Chihiro's story was shown. The silhouette of the characters from the anime are shown at the side in the 'eyecatches'.

In episode 1 at 21:26 mark you can see Konota from Lucky Star in display window in the background

In Episode 01, around 7:55, you can see a game being played that is most probably based off a popular danmaku game in Japan entitled Touhou: Project Shrine Maiden made by Team Shanghai Alice.

In Episode 9, Miyako's calling card design has the "Dango Daikazoku" from CLANNAD

In episode 9 at around 18:13, the inscriptions on the foreground gravestones bear some of the English lyrics for the theme song "Euphoric Field."

In episode 11 where Renji and Chihiro were near the crane game, Motsu from Negima!? is one of the prizes.

The opening movie of Episode 12 differs slightly from opening movie other episodes. In normal opening movie, the silhouettes of the three heroines shatter and disperse. However, in Episode 12 opening movie, they do not shatter but is carried away by three heroes respectively. Also, in normal episodes' opening movie, the silhouettes of Shindou sisters caught in chains shatter, however, in episode 12 opening movie, the sisters do not shatter but the chain does.